U.S Secretary of Education Arne Duncan speaks during a columnist conversation at the New York Times Schools For Tomorrow Conference Tuesday.

The next New York City mayor will take control of the nation’s largest school system. But don’t look to the U.S. Secretary of Education for guidance on which candidate would be best for the city’s 1.1 million public schoolchildren.

“I haven’t followed it that closely,” Secretary Arne Duncan said of the mayor’s race in an interview Tuesday.

Mr. Duncan, who spoke with reporters after an appearance at The New York Times Schools for Tomorrow conference, said he was a fan of Democratic nominee Bill de Blasio’s early-childhood proposal. Mr. de Blasio’s signature plan to increase taxes on the wealthy to pay for prekindergarten would need approval from Albany.

The Republican and Democratic nominees for the next New York City mayor have a few stark contrasts when it comes to how they would run the largest school district in the country. For one, Republican Joe Lhota embraces charter schools, while Mr. de Blasio has said he would charge charter schools rent.

Exit polls conducted by Edison Research showed that it wasn’t quite clear cut. For one, the top issue for de Blasio voters was jobs and unemployment, with education coming second. That echoed the top issues for the Democratic primary electorate overall.

When asked if schools were better or worse since Mr. Bloomberg took office in 2002, a third of de Blasio voters thought they have gotten worse, a third thought they were about the same, and a quarter thought they were better now, exit polls showed.

Mr. Duncan said the election didn’t mean that policies espoused by Mr. Bloomberg are dead. He compared the race to the Washington, D.C., election in which Mayor Adrian Fenty and his controversial schools chancellor Michelle Rhee were voted out of office.

“There’s lots of folks who said reform is over, it’s dead, all this stuff is going to come to a grinding halt,” he said. “It just simply wasn’t true.”

He continued: “Obviously I don’t know who the mayor is going to be in New York, but I assume anyone who’s going to be mayor wants their school system to be as strong as possible, will be held accountable for that, will want the best thing.”

And Mr. Duncan had praise for the Bloomberg administration.

“New York has made tremendous progress under Mayor Bloomberg,” he said. “This is hard. I thought I had a hard job in Chicago. It’s like two to three times more schools here in New York. I give Mayor Bloomberg and [schools Chancellor] Dennis Walcott tremendous credit for the hard work they’ve done. And the challenge, again, for, whether it’s de Blasio or the Republican candidate, can they take education achievements to the next level? That’s the challenge.”